Multi-ply fabric and friction elements embodying the fabric



July 23, 1957 F. HINDLE v MULTI-PLY FABRIC AND FRICTION ELEMENTS EMBODYING THE FABRIC 2 Sheets-Sheet 2 Filed Dec. 13, 1954 nited States Patent Othce MULTI-PLY FABRIC AND FRICTION ELEMENTS EMBODYING THE FABRIC FrankHindle, Rochdale, England, assignor to Turner Brothers Asbestos Company Limited, Manchester, England Application December 13, 1954, Serial No. 474,923

6 Claims. (Cl. 28-80) This invention relates to multi-ply fabrics of the kind in which the plies are all woven together and over their Whole area are united and maintained in face-to-face contact by binder threads that are parallel in plan to the warp threads and are Woven into the fabric at the same time. Such fabrics, when impregnated with a plastic, resin or other impregnant, are used as friction elements, e. g. as brake linings when the fabric consists principally of asbestos and as stair treads when the fabric consists of cotton. The binder threads pass from one face to the other and back again to hold the plies together. Commonly the binder threads are themselves arranged in pairs, one moving downwards while the other moves upwards, so that in a complete weaving cycle two weft threads are picked in each ply.

The common practice hitherto has been to have two binder threads working side by side. In one arrangement each binder thread, on reaching each face of the fabric, passes with at least one warp thread of the face ply round a weft thread. In another arrangement each pair of binder threads lies between pairs of warp thread and the threads adjacent to each binder thread are both on the opposite side of each face weft thread to it, but one is a binder and the other is a warp. It will be seen that when a fabric woven in either of these ways is viewed in plan there are two binder threads side by side, one passing round every alternate face weft thread and the other round the remaining face weft threads.

However many warp threads there may be to each pair of binder threads, the latter hear more heavily on the weft threads than the Warp threads do. Even though it is theoretically possible to maintain the tension at the desired value, it often happens in practice that it becomes too high. One source of error is the fact that the binder threads come from a beam under an initial tension which should be reduced as the beam becomes exhausted. The operator may not reduce this tension quickly enough, so that in part of the fabric the binder threads are under greater tension than was intended. Even if the weaving is carried on exactly as intended, the face of the fabric shows longitudinal grooves where the binder threads lie, and these grooves increase in depth as the tension in the binder threads increases. This is disadvantageous for three reasons. First, the appearance of the fabric suffers, being no longer uniform. Second, the face grinding which is commonly used after the impregnation processes to render the race of the impregnated fabric smooth must be increased if the face is grooved. Third, impregnated brake linings and the like are commonly made of the desired size by cutting the impregnated fabric by a saw, and if the cut is made along the line of a pair of binder threads, the impregnant in the groove may be broken away by the saw, so that the edge of the lining is rough.

It is an object of this invention to provide an improved multi-ply fabric so Woven as to overcome the disadvantages of the prior art.

It is another object of the invention to provide a novel Weave for a multi-ply fabric.

at one face, and preferably at both faces, each binder.

thread passes round every alternate face weft thread and lies between two face warp threads which pass on the inside of that weft thread. For maximum interlacing there is one binder thread in the fabric to every two warp threads in any ply, and both faces are woven alike. Then along the outside of each face weft thread two warp threads and one binder thread alternate.

The weave employed in the invention will be more clearly understood by reference to the accompanying drawings in which:

Figure 1 is a plan of part of a fabric;

Figure 2 is a similar view showing in exaggerated form the effect when the threads in the fabric are subjected to tension;

Figure 3 is a section on the line III-J11 in Figure 1 i and does not show any binder threads;

Figure 4 is a perspective view of the threads spaced apart from one another for the sake of clarity; and

Figures 5 and 6 show modifications of the weave, the binder threads not being shown.

The fabric shown in Figures 1 to 4 is three-ply. In the top ply there are warp threads 1, 2, 3 and 4 and weft threads 5 and 6. In the middle and bottom plies there are similar threads distinguished by the suflixes A and B respectively. Corresponding to all these threads there are two binder threads 7 and 8, distinguished by crosshatching in Figures 1, 2 and 4.

The fabric is woven with the three weft threads 5, 5A and 5B in the vertical plane, and the three threads 6, 6A and 6B in another vertical plane. A complete weaving cycle involves the introduction of these six weft threads, which may be picked in any desired order to give whatever selvedge is desired.

The warp threads 1 and 2 pass inside the weft thread 5 and outside the weft thread 6. The warp threads 3 and 4 do exactly the opposite. The warp threads in the middle and bottom plies are Woven exactly correspondingly to those in the top ply, i. e. (as seen in Figures 3 and 4) 1A and 1B pass under 5A and 5B and so on. The binder threads 7 and 8 run in opposite directions through the fabric from one face to the other, i. e. in the process of weaving one descends while the next is ascending and so on. This, of course, is readily done by providing two heald frames for the binder threads, one moving upwards and the other downwards at the end of each half cycle of operations of the shuttle when one weft thread has been introduced into each ply.

The binder thread 7 passes round the weft threads 5 and 6B, i. e. is outside the weft thread at each face. The binder thread 8 passes round the weft thread 53 and 6 and so is likewise outside the weft thread at each face. The binder thread 7 lies between the warp threads 1 and 2 and the thread 8 between the warp threads 3 and 4. Therefore at each face each binder thread in passing round a weft thread always lies between two warp threads which pass inside that weft thread.

If now the binder threads are subjected to a high tension, the exposed warp threads between two binder threads that pass round one weft thread tend to move towards one another as shown in exaggerated fashion in Figure 2, e. g. the warp threads 3 and 4 which pass round the weft thread 5 tend to move towards one another. In consequence there are no continuous longitudinal grooves on either face and the appearance of the fabric is much improved. When the impregnated fabric is cut, the edge 0 is smooth. However, there is at least as much interlac- Patented July 23, 1957 heald eye. The voids in the multi-ply fabric according to the invention aretherefore at least as many as m a appearance.

Since 1n a brake fining it is only the working face that is important, the-opposite facemay be woven in theway hitherto usual, or inany other way, but it is preferred to weave both faces alike.

parallel-in plan-to said warp threads, andat least at one 7 face each binder thread passing round every alternate face weft thread and lying between two immediately adjacent face warp threads which pass on the inside of that weft thread.

'2. A fabric comprising a plurality. of independent plies each comprising warp and weft threads, and binder threads uniting said plies over their whole area and maintaining 1 them in face-to-face contact, said binder threads being If the plies need not be very tightly bound the'ratio of binder threads to warp threads may '-be reduced by associatingmore Warp threads with each binder thread. The corresponding warp threads 1, 1A and 1B and so forth need not be i dentically Woven, but rather other arranger'nents may be used. For instance, as shown in Figure 5, where a warp thread 1 passes over a weft thread 5 in the top ply, the warp thread 1A at the exactly corresponding point in the next ply may pass: beneath its weft thread 5A, while the warp thread 1B passes over the weft thread 513. Again, as shown in Figure 6, the weft threads 1 and 1A may be identically woven, whereas the weft thread 1B is oppositely woven.

I claim:

l. A fabric comprising a plurality of independent plies each comprising warp and weft threads, and binder threads uniting said plies over their whole area and maintaining them .in face-to-face contact, said binder threads being parallel in plan to said warp threads, and at each face each binder thread passing round every alternate face weft thread and lying between two immediately adjacent face warp threads which pass on the inside of that weft thread.

3. Afabric as claimed in claim '2 'inwhich there is one binder thread in the fabric to every two warp threads in any ply.

4. A friction element comprising a multi-ply fabric 7 as defined in claim 1 impregnated with a plastic.

5. A fabric as claimed in claim 1 in which alternatebinder threads pass over alternate face weft threads.

7 '6. A fabric as claimed in claim 1 in which consecutive binder threads pass round different face weft threads.

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